An underlying object of the present invention is therefore to describe and refine a method for producing histological sections with a microtome, in which method the histological sections do not roll up, and in which method improved downline processing is possible.
In the method according to the present invention, the carrier material is cut out, prior to application, to at least one of a size and a shape that corresponds substantially to the cross-sectional area of the block; and that the cut-out carrier material is applied onto the block.
What has been recognized according to the present invention is firstly that when histological sections are produced, the advantages associated with the carrier material can be utilized, and the disadvantages associated in particular with the carrier material of U.S. Pat. No. 5,746,855 embodied as an endless strip can be avoided, if the carrier material is cut out, in terms of size and/or shape, in such a way that the cut-out carrier material corresponds to the cross-sectional area of the block. This results in histological sections that adhere to the cut-out carrier material or are mounted thereonto. The cut-out carrier material can be individually delivered, with the histological section mounted thereonto, in automated or manual fashion to a downline processing system, or the microtome operator can individually pick up the cut-out carrier material and the histological section mounted thereonto, for example with a forceps, and apply it onto a specimen slide. In this context, the histological section is applied onto the specimen slide with the surface of the histological section that faces away from the carrier material. The histological section is therefore then located between the carrier material and the specimen slide. It is thus not necessary to handle an endless strip having multiple histological sections applied thereonto, such that in some circumstances certain histological sections become damaged. The histological sections produced in accordance with the method according to the present invention correspondingly do not roll up, and improved downline processing, compared with the procedure using an endless strip as a carrier material, is thus advantageously possible.
According to a preferred embodiment, the carrier material is cut out with the application apparatus. The application apparatus is, accordingly, embodied suitably for cutting out the carrier material before application onto the block. This can be achieved, for example, in that the application apparatus comprises a cutting apparatus. According to this embodiment, therefore, the functions of cutting out and applying the carrier material are combined in the application apparatus. This is discussed in even further detail below.
According to a very particularly preferred embodiment, the carrier material is cut out immediately before the sectioning operation of the histological section. This is a good choice in particular when the carrier material can be cut out with the application apparatus. As a result, the carrier material is cut out, or produced in the appropriate size and/or shape, only when it is actually required. It is thereby possible, for example, to at least largely prevent contamination of the carrier material to be applied onto the block, for example due to the operator's fingerprints.
Very particularly preferably, the cross-sectional area of the cut-out carrier material is somewhat larger than the cross-sectional area of the block. The cross-sectional area of the cut-out carrier material is preferably dimensioned to be up to 10%, in particular approx. 5%, larger than the cross-sectional area of the block. This can be achieved by a corresponding configuration of a cutting tool given predefined dimensions of the block. If the cross-sectional area of the cut-out carrier material is thus configured to be somewhat larger than the cross-sectional area of the block and therefore of the histological section to be produced, an edge region of the carrier material exists, to which region the histological section does not extend. According to this embodiment, the edge region ideally extends entirely around the periphery of the histological section if the carrier material has been applied to the block and the histological section is thus arranged in centered fashion relative to the carrier material.
In a further preferred method step, the histological section that has been produced is transferred, with the applied carrier material, from the blade holder onto a specimen slide and/or is delivered to a downline processing system. This could be accomplished, for example, by the fact that the microtome operator removes the carrier material, with the histological section arranged thereon, using a forceps, and applies it onto a specimen slide or delivers it to another downline processing system. Alternatively thereto, provision could be made for automated transfer of the cut-out carrier material, with the histological section attached thereto, onto a specimen slide, for example using a transport device provided on the blade holder of the microtome and embodied in the form of a transport belt.
Once the histological section, together with the cut-out carrier material, has been applied onto a specimen slide or delivered to a downline processing system, provision is made in a preferred method step to remove or detach the carrier material from the histological section. This could be accomplished, for example, by the action of energy. For example, thermal energy in particular, e.g. of a thermal radiator or of an infrared lamp, could be used to detach the carrier material from the histological section.
Depending on the particular carrier material used, electromagnetic energy of a suitable light source, for example UV light, could also be used to detach the carrier material from the histological section. Alternatively or additionally, the histological section could be detached or removed from the cut-out carrier material by application of a liquid solution. Ultimately, the cut-out carrier material can be removed from the histological section with a specific method step that is suitable with regard to the properties of the carrier material.
According to a very particularly preferred embodiment, the cut-out carrier material is applied onto the block only when the histological section to be produced is to be applied onto a specimen slide and/or is to be delivered to a downline processing system. Accordingly, histological sections that are not be applied onto a specimen slide, or are not to be delivered to a downline processing system, do not have cut-out carrier materials applied onto them. Such histological sections can be, for example, sectioning waste or trimming sections that therefore have a not inconsiderable thickness and are to be produced initially from a block just clamped into the microtome, until the sectioning plane of the block has arrived at a tissue sample of interest. The blocks typically comprise tissue samples that are embedded in paraffin. By means of the paraffin, the blocks are connected to the cassette. The surface of a non-processed block is very rough as long as the block has not yet been cut. A trimming process requiring typically several cuts is necessary for obtaining a smooth surface and making sure the cut penetrates the tissue sample. These trimming cuts cannot be used and are disposed. For these trimming cut, of course no carrier material is applied since the trimming cuts are waste. Avoiding attachment of carrier material can for instance be achieved by stopping the motor, e.g. by simply switching it off.
To those cuts that finally have a smooth surface and penetrate the tissue sample, an apparatus according to the present invention (application apparatus) applies a carrier material onto a histological section to be produced with a microtome. In accordance therewith, a histological section of predefinable thickness is producible, with the microtome, from a block that comprises a tissue sample. Before production of the histological section, a carrier material can be applied with the application apparatus onto the block. According to the present invention, the carrier material can be cut out, before application, to a size and/or a shape that corresponds substantially to the cross-sectional area of the block; and the cut-out carrier material can be applied onto the block.
The apparatus according to the present invention is suitable in particular for carrying out the method according to the invention ; in order to avoid repetition, reference is therefore made to the foregoing portion of the Specification regarding the method features relevant thereto. The apparatus-related features of the method steps that are described or required are apparent, in this context, to a skilled artisan active in the present sector having knowledge of the disclosure of the foregoing portion of the Specification.
Very particularly preferably, the application apparatus comprises a cutting device with which a cut piece of the carrier material can be produced from the uncut carrier material, which piece can be applied onto the block. With the cutting device, therefore, a piece of predefinable size and/or shape is cut to shape or cut out from the uncut carrier material before said piece is applied onto the block.
A dispensing device could furthermore be provided, with which uncut carrier material is deliverable to the cutting device. Alternatively or additionally, a takeup device could be provided, with which the carrier material that is cut and not applied onto the block can be taken up. The provision of a dispensing device and/or a receiving device is useful in particular when the carrier material is embodied in the form of a strip, for example comparably to the strip-shaped carrier material known from U.S. Pat. No. 5,746,855. The dispensing device could receive a roller having strip-shaped carrier material wound on it, which roller can be replaced when the carrier material is consumed. In comparable fashion, the takeup device could comprise a roller onto which the cut material not applied onto the block can be applied.
Concretely, the cutting device could comprise a housing in which a cutting tool for cutting out the carrier material is movably arranged. If blocks having different sizes and/or shapes are to be processed with the microtome, it may be useful for the cutting device to comprise cutting tools of different sizes. Depending on the particular block to be processed, the appropriate cutting tool for cutting out the carrier material is then used.
According to a preferred embodiment, the carrier material to be cut out is guidable between the housing of the cutting device and a countermember. Suitable guidance means could be provided for this, for example guide rollers, with which the carrier material is guided in a predefinable direction. The countermember can be, for example, a plate or a plate-shaped component that comes into engagement with the cutting tools when the carrier material is cut out. The plate-shaped component could have an opening that corresponds substantially to the size and/or shape of the cut piece, so that after production of the cut piece, the cut-out carrier material can be transferred through the countermember and applied onto the block.
Concretely, the carrier material could be capable of being cut out by the fact that the cutting tool is movable in the direction of the countermember. This could be brought about, in particular, by the fact that the cutting tool is moved sufficiently far that it can be brought into contact with the countermember. If the countermember then has an opening, the cutting tool could be moved toward the countermember and past a portion of the countermember. In this case the shape of the portion of the cutting tool provided for cutting would need to be configured in a fashion substantially complementary to the opening of the countermember, so that the cutting tool can be moved partly through the opening and the carrier material is thereby cut out.
According to a preferred embodiment, the cutting device comprises a contact pressure element with which the cut-out carrier material can be moved or applied onto the block. Provision could be made, in particular, that the contact pressure element can be pressed with a predefinable pressure onto the block so as thereby to press the cut-out carrier material with the predefinable pressure onto the block, and thus apply the cut-out carrier material in substantially uniform fashion onto the block, and/or to ensure secure contact between the cut-out carrier material and the histological section.
To allow automation of the application operation, the cutting device, dispensing device, takeup device, and/or cutting tool can preferably be driven or moved in motorized fashion. At least one drive motor could be provided for this purpose, for example embodied in the form of a stepping motor or a DC motor. If the carrier material is delivered or discharged manually, and only the cutting tool of the cutting device is embodied in motorized fashion, only one drive motor or electric motor is required. If the carrier material is additionally delivered or discharged in motorized fashion, a further drive motor could be provided on the takeup device, which motor moves the carrier material from the dispensing device past the cutting device to the takeup device, or pulls it to the takeup device.
The microtome could be a rotary microtome, a sliding microtome, or a rotating disc microtome. The apparatus according to the present invention is preferably provided for a rotary microtome, although it is also usable with the other types of microtome. With a rotary microtome, the block that comprises at least one tissue sample is mounted on a cassette associated with the block. The cassette is clamped in a specimen holder of the microtome. The cassette together with the block is moved upward and downward, using the specimen holder, substantially in a vertical direction, and in that context moved (advanced) substantially in a horizontal direction, a predefinable distance toward the blade that is arranged in stationary fashion, thereby producing histological sections of a predefinable thickness that corresponds to the prefinable distance of the horizontal advance motion of the specimen holder. With a rotary microtome, the apparatus according to the present invention is to be arranged between the microtome operator and the block surface that is to be sectioned. This can, however, complicate access to the specimen holder and/or the blade holder of the microtome, and to the operating elements therefor. According to a preferred embodiment, a motion device is therefore provided with which the apparatus is transferable from a position spaced away from the block into a position in proximity to the block. With the motion device, the apparatus could therefore be moved a short distance (for example, a few centimeters) in a direction toward the block or away from it. Provision could be made, however, that with the motion device the apparatus can be transferred from a position from which the cut-out carrier material can be applied onto the block into a position in which the apparatus is movable largely out of the region in which the operator accesses the operating elements of the blade holder and/or of the specimen holder, for example to one side, upward, or downward. In this case the motion to be performed by the apparatus can be complex.
With a rotary microtome, for production of a histological section the block is transferred in a vertical direction from an upper position into a lower position. The surface of the block is thereby moved past the blade. The histological section is thereby produced. It may therefore be useful if the apparatus according to the present invention for application of a carrier material is arranged on the block, relative to the microtome, in such a way that the application apparatus is arranged in a position that is located substantially opposite the surface of the block in the upper vertical position of the block. The carrier material to be cut out can then accordingly be applied, using the application apparatus, onto the block when the latter is still in the upper position before production of the histological section.
The histological sample or tissue sample is preferably embedded in an embedding medium. A block is thereby formed. The cross section of the block is round and, in particular, of circular configuration. In other words the block, in the context of a circular cross section, preferably has a cylindrical or a truncated conical shape. The cross section or shape of a histological section from such a block is accordingly round or circular. Because of the round or circular cross sections, multiple such histological sections produced in succession, when they form a section strip, are therefore connected to one another only at connecting points that extend over a smaller region (ideally, for example, only at one contact point) than is the case for histological sections of rectangular cross section (in which the connecting point of two histological sections extends over an entire adjacent side surface). A section strip made up of histological sections having a round or circular cross section can therefore be split up more easily. This is also the case when the histological sections are each equipped with cut-out carrier material.
If the cross section of the block is rectangular or round, provision is then preferably made that the cross section of the carrier material to be applied onto the block is likewise embodied in rectangular or round, and in particularly circular, fashion. It is also conceivable in the context of a rectangular block cross section, however, to cut out and apply onto the block a respective carrier material that has a round or circular cross section. In this case the size of the cut-out carrier material is preferably selected in such a way that the entire histological section to be produced is covered with the carrier material. In other words, the diameter of the circular cross section of the carrier material is larger than the side lengths of the rectangular cross section of the block. The converse case is likewise conceivable. In this context the cross section of the block is round or circular. The cross section of the carrier material to be cut out could in this case be embodied in rectangular or square fashion, preferably in such a way that the entire histological section is covered with carrier material.
The carrier material is preferably embodied in the form of a strip. This makes possible simple handling of the carrier material, as was indicated in connection with the dispensing device and the takeup device.
To ensure that the histological section, with the cut-out carrier material mounted thereon, can easily be applied onto a specimen slide, according to a preferred embodiment an opening for reception of the specimen slide is provided on the blade holder, preferably not far away from the blade. The surface of the specimen slide received in the opening is substantially flush with the surface of the blade holder, at least on a side facing toward the blade. The histological section that has been produced is movable in the context of the sectioning operation at least partly onto the specimen slide received in the opening. With this feature, the histological section that has been produced, onto which the cut-out carrier material is applied, can be applied or slid, in almost automatic fashion along with the sectioning operation, onto the specimen slide. If applicable, the specimen slide can have a coating such that the histological section can be slid with as little friction as possible onto the specimen slide.
Very particularly preferably, the apparatus according to the present invention is provided on a microtome for producing histological sections.
There are various ways of advantageously embodying and refining the teaching of the present invention. In the following, the invention is explained in more detail by preferred exemplifying embodiments of the invention with reference to the drawings. In conjunction with the explanation of the preferred exemplifying embodiments of the invention with reference to the drawings, an explanation is also given of generally preferred embodiments and refinements of the teaching.